Programme in Health Services and Systems Research, Duke-NUS Medical School, Singapore.
Programme in Health Services and Systems Research, Duke-NUS Medical School, Singapore.
Econ Hum Biol. 2020 May;37:100860. doi: 10.1016/j.ehb.2020.100860. Epub 2020 Feb 8.
Public health taxes on less healthy food and beverage products have been shown to be effective in various settings. However, it is unclear if observed reductions in the quantity of taxed products purchased is a result of price increases due to the tax or the accompanying messaging and if the effects are influenced by the level of support for such taxes within the population. 941 adults residing in Singapore were randomized and asked to shop in one of four versions of a fully functional on-line experimental grocery store: 1) no tax control; 2) implicit tax showing only post-tax prices (i.e., 20 % higher than control prices) on high-in-calorie products; 3) fake tax showing pre-tax prices and a label falsely indicating that the price includes a 20 % tax on high-in-calorie products; and 4) explicit tax showing the same label as in 3) and an actual 20 % price increase applied to the high-in-calorie products. The proportion of high-in-calorie products purchased was 14 % in the control arm. We were unable to reject the null hypothesis of no effect in the implicit tax arm compared to control (0.08, 95 % CI -3.31 to 1.77) or in the fake tax arm compared to the control (2.59, 95 % CI -5.04 to 0.00) but observed a statistically significant 3.35 percentage point decrease (95 % CI -6.01 to -0.5) in the explicit tax arm compared to control. We were unable to reject the null hypothesis of no effect in any of the outcomes related to diet quality. Individuals who support the tax showed greater responsiveness to the explicit and fake taxes compared to those who do not (price elasticities of demand of -1.38 and -0.51 respectively). Results suggest that reductions in the proportions of high-in-calorie products purchased may be largely attributable to explicit messaging rather than to price increases. However, even when effective, policymakers should recognize that changes in purchasing patterns may not improve diet quality and that results may not generalize to other areas where levels of support differ.
在各种环境下，对低健康食品和饮料产品征收公共卫生税已被证明是有效的。然而，尚不清楚所观察到的购买征税产品数量的减少是由于税收导致的价格上涨，还是伴随而来的信息传递的结果，以及这些影响是否受到人群中对这类税收的支持程度的影响。941 名居住在新加坡的成年人被随机分配，并被要求在一个完全功能的在线实验性杂货店的四个版本之一中购物：1）无税控制；2）仅对高热量产品显示税后价格（即比对照价格高出 20%）的隐性税；3）虚假税显示税前价格，并附有标签，错误地表明价格包括对高热量产品征收 20%的税；4）显性税显示与 3）相同的标签，并对高热量产品实际应用 20%的价格上涨。在对照臂中，高热量产品的购买比例为 14%。我们无法拒绝隐性税与对照相比（0.08，95%置信区间-3.31 至 1.77）或与对照相比（2.59，95%置信区间-5.04 至 0.00）无效果的零假设，也无法拒绝假税与对照相比无效果的零假设（2.59，95%置信区间-5.04 至 0.00），但观察到显性税与对照相比有统计学意义的 3.35 个百分点下降（95%置信区间-6.01 至-0.5）。我们无法拒绝任何与饮食质量相关的结果中无效果的零假设。支持税收的个体对显性税和虚假税的反应大于不支持税收的个体（需求价格弹性分别为-1.38 和-0.51）。结果表明，购买高热量产品比例的降低可能主要归因于明确的信息传递，而不是价格上涨。然而，即使有效，政策制定者也应该认识到，购买模式的变化可能不会改善饮食质量，而且结果可能不适用于其他支持程度不同的领域。
